Translate the verbal expression into an equation and solve it? show all work.
the difference of twice a number and 7 is 9.

Difference means subtract
twice means multiply
2x - 7 = 9

Preferably, the battery can fit in a case with copper connectors at either end and then have the two copper wires going to the socket for the bulb so it will light up when the battery is emplaced in the case with either electrode in contact with each connector. in checking the options, i would say the 3rd case would be correct, with the bulb in contact with one electrode and the other electrode wire going from the other end of the battery to the bulb as well to make a circuit between positive and negative electricity.